A. Anatomical overlap between pain (black and purple regions), salience (purple regions), and autonomic networks (red and purple regions) in central nervous system. Amg: amygdala; ACC: anterior cingulate cortex; NTS: nucleus tractus solitarius of the medulla; OFC: orbitofrontal cortex; PAG: periacqueductal gray; PBN: parabrachial nuclei; PVN: paraventricular nucleus of the hypothalamus; SI: primary somatosensory cortex; SII: secondary somatosensory cortex; Th: thalamus.
B. Various ANS measurements (e.g., skin conductance response, heart rate, heart rate variability, pupil dilation, blood pressure) across different end-organs are related to pain. Because these end-organs are innervated by different branches of the autonomic nervous system and influenced by different mechanisms in the periphery, they provide non-overlapping information about arousal, and are best used in combination. *Many measures of HRV are parasympathetically mediated, but some measures are jointly influenced by both the sympathetic and parasympathetic nervous system. +Blood pressure in the vasculature is primarily controlled by the sympathetic nervous system, but parasympathetic control of the heart also influences blood pressure.